Change logger name in tests
Change logger name in tests

As of Flask 1.1.0, the logger now takes the same name as the flask
app[[1]]. Update our tests so we're looking in the right place for
expected error messages.

[1]: https://flask.palletsprojects.com/en/1.1.x/changelog/#version-1-1-0

alphagov/digitalmarketplace-api,alphagov/digitalmarketplace-api,alphagov/digitalmarketplace-api